This article discusses Hauke Brunkhorst’s account of cosmopolitan statehood. In order to demonstrate its novelty in comparison with other diagnoses of world statehood, the article first sketches out some core ideas on the concept of a world state. This sketch then serves as the basis in order to more closely recall and assess Brunkhorst’s account of the evolution of ‘cosmopolitan statehood’. The article then proceeds to argue that although there is nothing substantially wrong with Brunkhorst’s diagnosis, the hopes he invests in cosmopolitan statehood are probably too optimistic. This optimism results from the fact that he buys too deeply into Luhmann’s rather undercomplex account of functional differentiation in world society. A more nuanced differentiation theoretical account of contemporary world politics reveals a greater variety of forms than suggested by the simple juxtaposition between particularist and cosmopolitan forms of statehood. This also leads to caution against overblown optimism when it comes to the integrative performance of the latter.